在玩笑中模拟 useDispatch 并在功能组件中使用该调度操作来测试参数

Question

嗨，我正在使用 jest 和酶编写功能组件的测试。当我模拟单击时，组件的参数（使用 useState 的组件状态）会发生变化。当状态改变时，然后 useEffect 调用，在 useEffect 中，我在改变后使用参数调度一些异步操作。所以我想用我正在调度的动作来测试参数。为此，我想模拟调度。我怎样才能做到这一点？任何人都可以帮助我，在此先感谢。下面我分享代码。

组件.js

import React, { useEffect, useState } from 'react';
import PropTypes from 'prop-types';
import { useSelector, useDispatch } from 'react-redux';
import { useTranslation } from 'react-i18next';
import { clientOperations, clientSelectors } from '../../store/clients';
import Breadcrumb from '../../components/UI/Breadcrumb/Breadcrumb.component';
import DataTable from '../../components/UI/DataTable/DataTable.component';
import Toolbar from './Toolbar/Toolbar.component';

const initialState = {
  search: '',
  type: '',
  pageNo: 0,
  rowsPerPage: 10,
  order: 'desc',
  orderBy: '',
  paginated: true,
};

const Clients = ({ history }) => {
  const { t } = useTranslation();
  const dispatch = useDispatch();
  const totalElements = useSelector(state => state.clients.list.totalElements);
  const records = useSelector(clientSelectors.getCompaniesData);
  const [params, setParams] = useState(initialState);

  useEffect(() => {
    dispatch(clientOperations.fetchList(params));
  }, [dispatch, params]);

  function updateParams(newParams) {
    setParams(state => ({
      ...state,
      ...newParams,
    }));
  }

  function searchHandler(value) {
    updateParams({
      search: value,
      pageNo: 0,
    });
  }

  function typeHandler(event) {
    updateParams({
      type: event.target.value,
      pageNo: 0,
    });
  }

  function reloadData() {
    setParams(initialState);
  }

  const columns = {
    id: t('CLIENTS_HEADING_ID'),
    name: t('CLIENTS_HEADING_NAME'),
    abbrev: t('CLIENTS_HEADING_ABBREV'),
  };

  return (
    <>
      <Breadcrumb items={[{ title: 'BREADCRUMB_CLIENTS' }]}>
        <Toolbar
          search={params.search}
          setSearch={searchHandler}
          type={params.type}
          setType={typeHandler}
          reloadData={reloadData}
        />
      </Breadcrumb>
      <DataTable
        rows={records}
        columns={columns}
        showActionBtns={true}
        deletable={false}
        editHandler={id => history.push(`/clients/${id}`)}
        totalElements={totalElements}
        params={params}
        setParams={setParams}
      />
    </>
  );
};

组件.test.js

const initialState = {
  clients: {
    list: {
      records: companies,
      totalElements: 5,
    },
  },
  fields: {
    companyTypes: ['All Companies', 'Active Companies', 'Disabled Companies'],
  },
};

const middlewares = [thunk];
const mockStoreConfigure = configureMockStore(middlewares);
const store = mockStoreConfigure({ ...initialState });

const originalDispatch = store.dispatch;
store.dispatch = jest.fn(originalDispatch)

// configuring the enzyme we can also configure using Enjym.configure
configure({ adapter: new Adapter() });

describe('Clients ', () => {
  let wrapper;

  const columns = {
    id: i18n.t('CLIENTS_HEADING_ID'),
    name: i18n.t('CLIENTS_HEADING_NAME'),
    abbrev: i18n.t('CLIENTS_HEADING_ABBREV'),
  };

  beforeEach(() => {
    const historyMock = { push: jest.fn() };
    wrapper = mount(
      <Provider store={store}>
        <Router>
          <Clients history={historyMock} />
        </Router>
      </Provider>
    );
  });

 it('on changing the setSearch of toolbar should call the searchHandler', () => {
    const toolbarNode = wrapper.find('Toolbar');
    expect(toolbarNode.prop('search')).toEqual('')
    act(() => {
      toolbarNode.props().setSearch('Hello test');
    });
    toolbarNode.simulate('change');
****here I want to test dispatch function in useEffect calls with correct params"**
    wrapper.update();
    const toolbarNodeUpdated = wrapper.find('Toolbar');
    expect(toolbarNodeUpdated.prop('search')).toEqual('Hello test')



  })

});

Answer 1

[更新] 从那以后我的想法发生了巨大的变化。现在我认为模拟商店（使用redux-mock-store甚至改变其状态的真实商店） - 和包装组件<Provider store={mockedStore}>- 更加可靠和方便。检查下面的另一个答案。

如果您模拟，react-redux您将能够验证useDispatch调用参数。同样在这种情况下，您将需要重新创建useSelector的逻辑（这非常简单，实际上您不必使 mock 成为一个钩子）。同样使用这种方法，您不需要模拟商店或根本不需要<Provider>。

import { useSelector, useDispatch } from 'react-redux'; 

const mockDispatch = jest.fn();
jest.mock('react-redux', () => ({
  useSelector: jest.fn(),
  useDispatch: () => mockDispatch
}));

it('loads data on init', () => {
  const mockedDispatch = jest.fn();
  useSelector.mockImplementation((selectorFn) => selectorFn(yourMockedStoreData));
  useDispatch.mockReturnValue(mockedDispatch);
  mount(<Router><Clients history={historyMock} /></Router>);
  expect(mockDispatch).toHaveBeenCalledWith(/*arguments your expect*/);
});

Answer 2

import * as redux from "react-redux";
describe('dispatch mock', function(){    
    it('should mock dispatch', function(){
            //arrange
            const useDispatchSpy = jest.spyOn(redux, 'useDispatch'); 
            const mockDispatchFn = jest.fn()
            useDispatchSpy.mockReturnValue(mockDispatchFn);

            //action
            triggerYourFlow();

            //assert
            expect(mockDispatchFn).toHaveBeenCalledWith(expectedAction);

            //teardown
            useDispatchSpy.mockClear();
    })
}});

从功能组件我们模拟上面的调度以停止它执行真正的实现。希望能帮助到你！